Responses of earliness and lateness genes for heading to different photoperiods, and specific response of a gene or a pair of genes to short day length in rice

Birendra Bahadur Rana,Mukunda Bhattarai,Yohei Koide,Misa Kamimukai,Masayuki Murai

doi:10.1186/s41065-019-0109-5

Birendra Bahadur Rana, Mukunda Bhattarai + Show 3 more

Open Access

https://doi.org/10.1186/s41065-019-0109-5

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Abstract

BackgroundHeading time is an important trait for regional and seasonal adaptabilities in rice, and is controlled by genetic factors in relation with environmental factors, mainly day length and temperature. The following genes controlling heading were examined for their responses to six different environmental conditions involving different day lengths using five early near-isogenic lines (NILs) of T65-R and three late NILs of T65wx: two earliness genes, Ef1 and Efx controlling basic vegetative phase (BVG), and m-Ef1, the enhancer to the former gene; and two lateness genes, Se1-pat(t) and se-pat controlling photo-sensitivity and BVG, respectively. T65-R and T65-T were different accessions of Taichung 65. T65wx is a NIL of T65-T carrying wx.ResultsThe five early NILs of T65-R were in the order of ER50 (Ef1, Efx, m-Ef1) < ER40 (Ef1, m-Ef1) ≤ ER20 (Ef1, Efx) < ER1 (Ef1) ≤ ER21 (Efx) < T65-R regarding days to heading (DTH) under two spring-sowing and one summer-sowing paddy field (PF) conditions. The three late NILs of T65wx were in the order of LF3 (Se1-pat(t)) ≤ LF2 (Se1-pat(t), se-pat) ≤ T65wx < LF1 (se-pat) under two short-day conditions (10-h photoperiod condition with artificial-light and natural short-day condition from autumn to winter). The NILs and T65wx were in the order of T65wx < LF3 < LF1 < LF2 under the two spring-sowing PF (long day) conditions. T65-R (Ac-ef1) was 2.8 or 5.1 days earlier in DTH than T65-T (ac-ef1) under the two spring-sowing PF conditions. However, T65-R was 19 and 10 days earlier than T65-T under the two short-day conditions.ConclusionsEarliness gene(s) and their combinations reduced DTH regardless of photoperiod lengths. Se1-pat(t) increased DTH under long-day conditions but decreased it under short-day conditions, while se-pat elongated DTH under both short-day and long-day conditions indicating that se-pat is responsible for BVG. The se-pat increased DTH by adding its effect over that of Se1-pat(t) under long-day conditions. However, this increasing effect of DTH by se-pat was almost completely masked when it coexisted with Se1-pat(t) under the short-day conditions. Notably, the response of Ac-ef1 to day length was found to delay heading under the short-day conditions.

Highlights

Heading time is an important ecological characteristic in rice, and is related to regional and seasonal adaptabilities [2, 21, 40]
According to Okumoto et al [21], a lateness gene controlling photo-sensitivity, E1, is commonly harbored in early, middle, and late heading varieties grown in south-western region of Japan, and another photo-sensitivity gene, E2, and/or other genes are related to the variation in heading time
Day lengths at the critical stage for preparing panicle development under the paddy field (PF) and Natural light (Nat-L) chamber conditions, and monthly average temperatures in the experimental years in the PF Table 3 shows day lengths at 35 days before heading in the early near-isogenic lines (NILs), T65-R, T65-T, T65wx and the late NILs which were calculated from daily sunrise and sunset times in the three experimental years in the PF, and autumn to winter in 2013–2014 in the Nat-L growth chamber, being taken from the database of National Astronomical Observatory of Japan

Summary

Introduction

Heading time is an important ecological characteristic in rice, and is related to regional and seasonal adaptabilities [2, 21, 40] It is controlled by genetic factors in relation with environmental factors, mainly day length and temperature. The BVG phase is the minimum duration of vegetative growth from sowing to initiation of panicle development under the condition of short day (“SD”) and higher temperature. Heading time is an important trait for regional and seasonal adaptabilities in rice, and is controlled by genetic factors in relation with environmental factors, mainly day length and temperature.

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