Is the genetic variability of elite rice in southern Brazil really disappearing?

Abstract

There is a worldwide concern about a possible narrowing of the genetic base of most crops, as e.g. that of rice (Oryza sativa L.), as a result of the modern breeding practices. Thus, the purpose of this study was to investigate this phenomenon in the germplasm of elite paddy rice in southern Brazil, including frequently used accessions in crosses. The panel consisted of 91 accessions. Data of morphological traits, SNP markers and mineral content of husked and polished grain were analyzed by hierarchical clustering and principal component analysis. The SNP markers and hierarchical clustering proved most appropriate to assess the genetic variability. A narrowing of the genetic base of rice was confirmed, although a certain level of genetic variability was still found in the germplasm of elite paddy rice in south Brazilian rice, particularly for grain mineral content.

Quarter century genetic progress in irrigated rice (Oryza sativa) in Southeast Brazil

“…Despite of the stagnation in grain yield for the irrigated rice breeding programme for the Southeast Region, due to the great national and international demand for rice grain, it is necessary to seek greater gains in grain yield. One of the main factors contributing to these results is the decrease in genetic variability among elite rice lines in recent years, as reported by Busanello et al (2020) and Costa et al (2020). Factors such as limited genic combinations and genetic drift in the breeding population also decrease the rate of genetic gain and compromise long‐term response to selection (Bernardo, 2010; Falconer & Mackay, 1996; Müller et al, 2017).…”

Dynamics, diversity and experimental precision in final irrigated rice testing: a time meta-analysis

“…These results show that the progenies of high-performing parents will also tend to have a high performance (Borem et al 2017), indicating a greater chance of success with selection in the breeding program (Vasconcelos et al 2012). However, this heritability value decreased over time (Figure 2), suggesting which the narrowing of the genetic base of rice mentioned for Busanello et al (2020) in southern Brazil also was confirmed in the Minas Gerais, requiring an effort to increase parental diversity. Aside from the search for alternatives to increase genetic variability, superior cultivars must be crossed to form a base population, as recommended by Santos et al (2019).…”

Analysis of the genetic structure and diversity of a Brazilian macadamia nut (Macadamia integrifolia) germplasm

“…Currently, only 1% of the Australian rainforest is preserved and restricted into fragments (Sobierajski 2019). This scenario emphasizes the importance of well-characterized ex situ germplasms (Busanello et al 2020, Guan et al 2020, Carena 2021. The genetic variation existing in germplasms can provide genes for resistance to pests, diseases and adaptation to climate changes (Topp et al 2019, Carena 2021.…”