Mapping chromosomal regions associated with anther indehiscence with exerted stigmas in CRI-48 and Jasmine 85 cross of rice (Oryza sativa L)

Abstract

Anther indehiscence in certain wide crosses combines male sterility with stigma exertion, a phenomenon that is desirable for hybrid rice seed production. This study sought to identify chromosomal region(s) that combine anther indehiscence with exerted stigmas. A mapping population consisting of 189 BC 1 F 1 plants was derived from a cross between CRI-48 and Jasmine 85 and backcrossing the resulting F 1 to Jasmine 85. Contrary to the three complementary genes mode of inheritance reported earlier, a single locus (AI6-1) was mapped on chromosome 6 at 27.4 cM for anther indehiscence with exerted stigmas through a mixed model-based composite interval mapping (MCIM). This locus was flanked by two single nucleotide polymorphism (SNP) markers, K_ID6002884 and K_ID6003341 within a range of 23.1-28.9 cM. The allele at the locus was contributed by the CRI-48 parent which has Oryza glaberrima ancestry. This locus is suggested to control anther indehiscence and stigma exertion through pleiotropic gene action or cluster of genes.

Fine-Mapping and Candidate Gene Analysis of qSERg-1b from O. glumaepatula to Improve Stigma Exsertion Rate in Rice

“…Hybrid rice played a very important role in boosting rice production over the past few decades. Since the success of hybrid rice being developed and planted widely in China in 1970s, the rice yield per unit area has been improved greatly by at least 20-30% compared with conventional inbred rice [1][2][3]. Nowadays, hybrid rice has extended to the other main rice-producing countries in Asia and has vital roles in ensuring food security [4], such as in Bangladesh, the fourth highest rice-producing country worldwide [2,[4][5][6].…”

“…However, the low F 1 seed yield is known as the bottleneck for hybrid rice extension and commercialization. The hybrid F 1 seed is produced through the outcrossing process between the male sterile lines and the restorer lines [7], and the outcrossing rate is significantly correlated with the stigma exsertion rate (SER) of the male sterile lines [3,8]. In other words, the more spikelets with exserted stigma in a panicle of a male sterile plant, the more hybrid seeds would be produced, because the spikelets with exserted stigma receive pollen grains from the restorer lines more easily.…”