Trials for hybrid seed production and estimation of wheat F1 hybrids produced by outcrossing using photoperiod-sensitive cytoplasmic male sterile (PCMS) system with elite lines

Abstract

In previous studies, we presented a two-line system for producing hybrid varieties in common wheat (Triticum aestivum L.) based on photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by the cytoplasm of relative wild species Aegilops crassa L. We have developed several promising elite PCMS lines with the genetic background of Japanese wheat cultivars, which showed high cross-pollination fertility and high male sterility under long-day conditions and high seed fertility under short-day conditions. Here, we performed an F1 seed production trial between eight elite PCMS lines and the pollinator variety 'Fortunato', which has high combining ability with the PCMS elite lines, under longday conditions in Hokkaido, Japan. Two of eight PCMS lines showed complete sterility and had more than 50% open pollination fertility. Using the F1 seeds obtained, the agronomic characters of five F1 hybrids were examined under shortday conditions in Fukui, Japan. The F1 hybrids headed 4 to 5 days earlier than the early-heading elite leading cultivar of Fukui, 'Fukukomugi'. Compared with 'Fukukomugi', yield heterosis of F1 hybrids ranged from 21 to 61% in small plot trials. The results of the present study suggested the practicality of using this PCMS system for hybrid wheat production.

Hybrid wheat breeding using photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by <i>Aegilops crassa</i> cytoplasm

“…F 1 hybrid seeds between an elite PCMS line and ʻFortunatoʼ were generated by outcrossing spring-sown plants at Hokkaido under LD conditions (Fig. 2) (Murai et al 2019). The PCMS line seeds were sown in one row at a seeding density of 50 seeds m 1 in a crossing block of 1 m length; each block was surrounded by two rows, 30 cm apart, of the pollinator line at a seeding density of 100 seeds/m.…”

“…The performance of the F 1 hybrids was examined at autumn sowing in Fukui under SD conditions (Murai et al 2019). The F 1 hybrids headed 4 to 5 d earlier than the early-heading elite leading cultivar of ʻFukukomugi.ʼ Compared with ʻFukukomugi,ʼ yield heterosis of F 1 hybrids ranged from 21 to 61% in small plot trials.…”

Effects of cytoplasm from the related wild species <i>Aegilops mutica</i> on agronomic characters in Japanese bread wheat cultivars

“…Of the wheat CMS systems found by Prof. Tsunewaki, that produced using Ae. crassa cytoplasm has been the most widely exploited and has led to the development of practical hybrid wheat varieties (Murai et al 2016(Murai et al , 2019. In addition to CMS, alien cytoplasm can cause germless grain formation, premature sprouting, twin seedling formation, variegation under low temperature, depressed growth vigor, and delayed heading time (Tsunewaki 1993).…”