Crinkly4 receptor-like kinase is required to maintain the interlocking of the palea and lemma, and fertility in rice, by promoting epidermal cell differentiation.

The palea and lemma are unique organs in grass plants that form a protective barrier around the floral organs and developing kernel. The interlocking of the palea and lemma is critical for maintaining fertility and seed yield in rice; however, the molecules that control the interlocking structure remain largely unknown. Here, we showed that when OsCR4 mRNA expression was knocked down in rice by RNA interference, the palea and lemma separated at later spikelet stages and gradually turned brown after heading, resulting in the severe interruption of pistil pollination and damage to the development of embryo and endosperm, with defects in aleurone. The irregular architecture of the palea and lemma was caused by tumour-like cell growth in the outer epidermis and wart-like cell masses in the inner epidermis. These abnormal cells showed discontinuous cuticles and uneven cell walls, leading to organ self-fusion that distorted the interlocking structures. Additionally, the faster leakage of chlorophyll, reduced silica content and elevated accumulation of anthocyanin in the palea and lemma indicated a lesion in the protective barrier, which also impaired seed quality. OsCR4 is an active receptor-like kinase associated with the membrane fraction. An analysis of promoter::GUS reporter plants showed that OsCR4 is specifically expressed in the epidermal cells of paleas and lemmas. Together, these results suggest that OsCR4 plays an essential role in maintaining the interlocking of the palea and lemma by promoting epidermal cell differentiation.

[Location of the fertility restorer gene for T-type CMS wheat by microsatellite marker].

Through the genetic analysis of a F2 population, derived from CMS line 75-3369A (T-type CMS wheat) and the restorer line 7269-10, the result indicated that the restorer line was conditioned by two dominant genes. A F2 population was used to map the fertility restorer (Rf) gene by microsatellite and BSA (bulked segregant analysis). Restorer and sterile DNA pools were established using the extreme fertile and sterile plants of F2 population, respectively. Among the 230 pairs of microsatellite primers, two markers were found polymorphic between the two pools. Linkage analysis showed that microsatellite marker Xgwm136 and Xgwm550 were linked with the two fertility restorer genes, respectively. One of the Rf gene was located on 1AS and the genetic distance between the SSR marker Xgwm136 and this Rf gene was 6.7 cM, the other Rf gene was located on 1BS and with a genetic distance of 5.1 cM to marker Xgwm550.