Genetic Mapping Of Morpho-Physiological Traits Involved During Reproductive Stage Drought Tolerance In Rice

Abstract

13Reproductive stage drought stress is an important factor for yield reduction in rice. Genetic 14 mapping of drought responsive QTLs will help to develop cultivars suitable for drought 15 prone environments through marker-assisted breeding. QTLs linked to morpho-physiological 16 traits under drought stress were mapped by evaluating 190 F 7 recombinant inbred lines (RIL). 17Significant variations were observed for eleven morpho-physiological traits involved during 18 the stress. Bulked segregant analysis (BSA) strategy was adopted for genotyping the RIL 19 population. A total of 401 SSR primers were tested for parental polymorphism of which 77 20 were polymorphic. Inclusive composite interval mapping detected a total of five consistent 21 QTLs controlling leaf rolling (qLR 9.1 ), leaf drying (qLD 9.1 ), harvest index (qHI 9.1 ), spikelet 22 fertility (qSF 9.1 ) and relative water content (qRWC 9.1 ) under reproductive stage drought stress. 23 Another two non-allelic QTLs controlling leaf rolling (qLR 8.1 ) and leaf drying (qLD 12.1 ) were 24 linked in a single year. QTL controlling leaf rolling, qLR8.1 was validated in this mapping 25 population and useful in marker-assisted breeding (MAB) programs. Out of these five 26 consistent QTLs, four (qLR 9.1, qLD 9.1, qHI 9.1 and qRWC 9.1 ) were detected to be novel QTLs 27 and useful for MAB for reproductive stage drought tolerance in rice. 28 29 drought tolerance, QTL mapping, 30 31 34Majority of the global population consume rice as their staple food. Rice provides food and 35 livelihood security to 90% of people in Asia and South-east Asia. Globally, rice crop covers 36 about 160.8 million hectares with total production of more than 725.5 million tons of paddy 37 per annum [1]. The targeted food production need to be increased even from the drought-38 prone areas with an increase of 40% from this difficult ecosystem by 2025 [2]. Drought is the 39 major limitation in getting higher production from rainfed rice cultivation [3]. It affects the 40 crop at vegetative and reproductive growth stages. Under water stress, genotype showing 41 delay in leaf rolling and faster recovery from the stress are required for drought breeding [4]. 42During vegetative stage, leaf rolling and leaf drying are good criteria of screening drought 43 tolerance [5][6][7]. Drought stress during reproductive stage is most critical as it causes low yield 44 due to higher proportion of unfilled grains in the panicles [7,[9][10][11][12]. 45Drought is the major abiotic stress responsible for cultivation of rice mostly in rain-46 fed upland and lowland areas, worldwide. In Asia, about 34 million hectares of rain-fed 47 lowland and 8 million hectare of upland rice are affected by frequent drought stress in each 48 year. In India also, during the recent years, climate change is altering the rainfall pattern 49 affecting rice production to a greater extent. Although rice production is increasing by 2.8% 50 annually, damage caused by biotic and abiotic factors accounted for a heavy loss of glo...

Genetic mapping of physiological traits associated with terminal stage drought tolerance in rice

“…The PCR was performed in a thermal cycler (Applied-Biosystems) described in the publication [ 50 ] using the simple sequence repeat primers (Tables 4 and 5 ). The reaction mix for the PCR included 30 ng genomic DNA, 1 X reaction buffer (1.5 mM Tris-HCl, 50 mM KCl, 2 mM MgCl2), 10 mM dNTPs, 1 U Taq polymerase and 5 pmole each of forward and reverse primers.…”

“…Data on ten physiological traits (leaf length, leaf width, biomass, chlorophyll a, chlorophyll b, chlorophyll a + b, chlorophyll a/b, relative chlorophyll content, proline content and cell membrane stability) and grain yield of 190 recombinant inbred lines and parents were used for construction of linkage map as described in the earlier publication [ 50 ]. The linkage map was generated by employing ICIM (inclusive composite interval mapping) v4.0 software [ 73 ].…”

“…QTL mapping study in Bala/Azucena reported 24 QTLs controlling various morphological, physiological and root related traits under drought stress, explained 4.6 to 22.3% phenotypic variance [ 49 ]. Five consistent QTLs were reported for various morphological and physiological traits linked to drought stress tolerance during terminal stage in rice [ 50 ].…”

Genetic Relationship and Structural Variation of Root Growth Angle for Deep Rooting in Rice (Oryza sativa L.)

“…Water stress causes severe damage to plant, at different stages of its life cycle, viz. vegetative and reproductive stages [8,9], resulting in huge loss of productivity [10]. Plants respond to such external stimuli by various adaptative mechanism viz., better root architecture [11], better osmotic adjustment, higher leaf water potential [12], so as to adapt to the stress environment.…”

Bulk analysis by resequencing and RNA‐seq identifies candidate genes for maintaining leaf water content under water deficit in maize

“…Moreover, LRWC is a highly heritable trait (broad-sense heritability of 0.71-0.94) (Maheswari et al, 2016). The genetic basis of the LRWC under water deficit has been identified in wheat (Rad et al, 2012), rice (Barik et al, 2019;Singh, 2018), cotton (Saleem et al, 2015), sunflower (Abdi et al, 2013), barley (Teulat et al, 2003), and soybean (Virginia et al, 2012;Vu et al, 2015). In maize, compared to other traits such as yield and anthesis and silking interval (ASI) under water deficit, QTL mapping of LRWC is relatively few.…”