Drought is the leading threat to agricultural food production, especially in the cultivation of rice, a semi-aquatic plant. Drought tolerance is a complex quantitative trait with a complicated phenotype that affects different developmental stages in plants. The level of susceptibility or tolerance of rice to several drought conditions is coordinated by the action of different drought-responsive genes in relation with other stress components which stimulate signal transduction pathways. Interdisciplinary researchers have broken the complex mechanism of plant tolerance using various methods such as genetic engineering or marker-assisted selection to develop a new cultivar with improved drought resistance. The main objectives of this review were to highlight the current method of developing a durable drought-resistant rice variety through conventional breeding and the use of biotechnological tools and to comprehensively review the available information on drought-resistant genes, QTL analysis, gene transformation and marker-assisted selection. The response, indicators, causes, and adaptation processes to the drought stress were discussed in the review. Overall, this review provides a systemic glimpse of breeding methods from conventional to the latest innovation in molecular development of drought-tolerant rice variety. This information could serve as guidance for researchers and rice breeders.

Currently, the global agricultural system is focused on a limited number of crop species, thereby presenting a threat to food security and supply, especially with predicted global climate change conditions. The importance of ‘underutilized’ crop species in meeting the world’s demand for food has been duly recognized by research communities, governments and policy makers worldwide. The development of underutilized crops, with their vast genetic resources and beneficial traits, may be a useful step towards solving food security challenges by offering a multifaceted agricultural system that includes additional important food resources. Bambara groundnut is among the beneficial underutilized crop species that may have a positive impact on global food security through organized and well-coordinated multidimensional breeding programs. The excessive degrees of allelic difference in Bambara groundnut germplasm could be exploited in breeding activities to develop new varieties. It is important to match recognized breeding objectives with documented diversity in order to significantly improve breeding. This review assesses the genetic diversity of Bambara groundnut, as well as important factors involved in realizing and harnessing the potential of this crop.

Flooding or submergence is one of the major environmental stressors affecting many man-made and natural ecosystems worldwide. The increase in the frequency and duration of heavy rainfall due to climate change has negatively affected plant growth and development, which eventually causes the death of plants if it persists for days. Most crops, especially rice, being a semi-aquatic plant, are greatly affected by flooding, leading to yield losses each year. Genetic variability in the plant response to flooding includes the quiescence scheme, which allows underwater endurance of a prolonged period, escape strategy through stem elongation, and alterations in plant architecture and metabolism. Investigating the mechanism for flooding survival in wild species and modern rice has yielded significant insight into developmental, physiological, and molecular strategies for submergence and waterlogging survival. Significant progress in the breeding of submergence tolerant rice varieties has been made during the last decade following the successful identification and mapping of a quantitative trait locus for submergence tolerance, designated as SUBMERGENCE 1 (SUB1) from the FR13A landrace. Using marker-assisted backcrossing, the SUB1 QTL (quantitative trait locus) has been incorporated into many elite varieties within a short time and with high precision as compared with conventional breeding methods. Despite the advancement in submergence tolerance, for future studies, there is a need for practical approaches exploring genome-wide association studies (GWA) and QTL in combination with specific tolerance traits, such as drought, salinity, disease and insect resistance.Sustainability 2020, 12, 1632 2 of 16 yield losses annually. For example, as reported by Bailey-Serres et al. [2], in the United States, a 12-year study on losses of crop production revealed that flooding is the second threat after drought. It was reported that these two abiotic stresses (flooding and drought) accounted for a 70% drop in harvest in 2011 alone. In that year, there were insurance payouts of over 3 billion USD due to flooding, with over 1.6 billion paid on soybean and maize. In Pakistan, over 4.45 billion USD worth was lost due to flooding in rice, cotton, and wheat in 2010 [3]. Similarly, an increase in summer rainfall causes water stagnation and flooding, with the event of economic consequences across Europe [4].At the moment, one of the most flood-threatened crops is rice. About 30% (700 million) of people living in abject poverty (i.e., daily income less than 1$) in Asian countries reside in flood-prone rice cultivating regions of South Asia, with Nepal, Bangladesh, and India accounting for half of the above-stated figure. In Nepal, 15% of the total cultivated areas of 1.5 million hectare is affected by floods every year [5]. Similarly, out of 16.1 million hectares of rice-growing areas in India, 5.2 million are occasionally affected by flood, while in Bangladesh, 1.6 million hectares of rice field are periodically affected by flood, out of a tot...

Brown planthopper (BPH; Nilaparvata lugens Stal) is considered the main rice insect pest in Asia. Several BPH-resistant varieties of rice have been bred previously and released for large-scale production in various rice-growing regions. However, the frequent surfacing of new BPH biotypes necessitates the evolution of new rice varieties that have a wide genetic base to overcome BPH attacks. Nowadays, with the introduction of molecular approaches in varietal development, it is possible to combine multiple genes from diverse sources into a single genetic background for durable resistance. At present, above 37 BPH-resistant genes/polygenes have been detected from wild species and indica varieties, which are situated on chromosomes 1, 3, 4, 6, 7, 8, 9, 10, 11 and 12. Five BPH gene clusters have been identified from chromosomes 3, 4, 6, and 12. In addition, eight BPH-resistant genes have been successfully cloned. It is hoped that many more resistance genes will be explored through screening of additional domesticated and undomesticated species in due course.

The world’s food and agricultural programs have gradually declined into an unsustainable situation due to challenges such as increase in world population, varied agro-climatic regions, increase temperature, extreme sole-culture growing techniques, and water shortage. A considerable emphasis has been put on few staple food crops coupled with repeated dieting, food scarcity, and essential mineral deficits, frequently inducing dietary disorders. Because relying on staple crops may lead to serious food shortages in the future, we must adjust our dietary habits to include a diverse range of non-staple foods and maximize their use in order to achieve food security and reduce the nutritional gap. To assure healthy meals around the world, an authentic and reasonable strategy is presented to draw additional awareness towards variations in agricultural production techniques and dietary preferences. The EAT-Lancet declaration highlighted the importance of increasing agri-based foods to achieve sustainable health. Expanding overlooked crops with abundant genetic stocks and possibly beneficial characteristics is an approach that might meet food and nutritional security challenges. Although undervalued, pumpkin is a valuable vegetable herbaceous plant that contributes to global food and nutritional security. This crop has already been identified as a revolutionary age crop, balanced food, and more adapted to low soil and atmospheric circumstances than other major crops. This review paper focuses on the potential uses of pumpkin as an underutilized crop; diversification and development of hybrids, particularly hybridization breeding through diallel mating design; and how implementation of this “modern” technology would contribute to the breeding of the neglected pumpkin vegetable and stimulate productivity and nourish the world’s largest malnourished, deprived, and starved populations.

Bacterial leaf blight caused by Xanthomonas oryzae pv oryzae (Xoo) and blast caused by Magnaporthe oryzae are major diseases responsible for significant yield loss in rice production across all rice growing regions. Host plant resistance has been advocated as a sustainable means of guarding against the diseases. This experiment was conducted with the aim to introgress multiple resistance genes against bacterial leaf blight and blast diseases through marker-assisted backcross breeding. Two dominant (Xa4 and Xa21) and two recessive (xa5 and xa13) Xoo resistance genes were introgressed into a high yielding Malaysian rice variety Putra-1 with genetic background of three blast resistance (Piz, Pi2 and Pi9) genes. Eight polymorphic tightly linked functional and SSR markers were used for foreground selection of target genes. Seventy nine polymorphic SSR markers were used in background selection. The plants were challenged at initial stage of breeding and challenged again at BC2F2 with the most virulent Malaysian pathotypes of Xoo (P7.7) and Magnaporthe oryzae (P7.2) to test their resistance. Results obtained from foreground marker segregation analysis at BC1F1 and BC2F1 showed that the marker polymorphism both fitted into the Mendel’s single gene segregation ratio of 1:1 for both Xoo and blast resistance. At BC2F2, results indicated that foreground marker polymorphism fitted into the expected Mendelian ratio of 1:2:1 for blast resistance only. Marker-assisted background selection revealed high percentage of recurrent parent genome recovery (95.9%). It was concluded that the inheritance of blast resistance in the introgressed lines was mainly due to single gene action while the inheritance of Xoo resistance was substantially due to single nuclear gene action. The incorporation of four bacterial leaf blight and three blast resistance genes (Xa4 + xa5 + xa13 + Xa21; Pi9 + Pi2 + Piz) in the newly developed lines would provide for broad spectrum and durable resistance against the two major diseases studied.

Grafting is regarded as an integral component of sustainable vegetable production. It is important in the management of soil-borne diseases, and reports suggest that grafting with viable rootstocks can enhance crop growth and yield. This research was conducted using splices and cleft grafting techniques to investigate graft compatibility among varieties of high yielding eggplant scion (MCV1, MCV2, CCV1, CCV2, CCV3, NCV, and TCV) grafted onto wild rootstocks (MWR, BWR, and TWR) to study their morphophysiological and yield characteristics. High yielding scions grafted onto wild relative rootstocks were compared with two controls including self-grafted and non-grafted. All the scion had a high rate of germination (≥95%) and remarkable graft success (100%) was recorded in MCV1, MCV2, and TCV using the cleft techniques. Generally, the use of rootstocks resulted in higher total and marketable fruit yield compared to the non-grafted and self-grafted scion plants, respectively. In particular, MWR and TWR rootstock conferred the highest vigour to the scion, resulting in the highest values recorded for total and marketable fruit yield, number of fruits per plant and average fruit weight. A similar result was obtained in fruit length and diameter, where long and wide fruits were observed in scions grafted onto MWR and TWR rootstocks, respectively. Grafting of high yielding eggplant scion onto resistant MWR, BWR and TWR eggplant rootstock was found to be beneficial for eggplant cultivation. The remarkable compatibility and vigour of the rootstock with scion led to the improvement in total and marketable yield of the fruits. As such, it can be concluded that the use of wild relative rootstocks of eggplant species can be a valuable method of improving eggplant production.

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