FA controls flowering time of first and successive inflorescences of tomato
In fa plants, the number of leaves below first and subsequent inflorescences, a feature that is highly correlated with flowering time in different plant species, is approximately double that found in wild-type plants. This feature, together with the fact that the initiation of fainflorescence occurs approximately 2 weeks later than in the wild type, demonstrates that fa is a late-flowering mutant. Delay in flowering time has also been detected in lfy ( Blazquez et al. 1997 ), but not in flo ( Coen et al. 1990 ), uni ( Hofer et al. 1997 ) or alf ( Souer et al. 1998) mutants. In Arabidopsis, flowering time of lfy mutants, 35S::LFY plants, and transgenic plants with an increased copy number of endogenous LFY reveals that LFY controls flowering initiation ( Blazquez et al. 1997 ; Nilsson et al. 1998 ). The detailed expression analysis of LFY during the vegetative phase of development has suggested that the level of LFY expression is a critical point for flower initiation, and that the required LFY level changes with the age of the plant ( Blazquez et al. 1997 ). Young vegetative meristem would therefore be much less competent to respond to LFY activity and would need higher levels of LFY expression to initiate flowering than required by older meristems. Based on the fa mutant phenotype, the transition to flowering in tomato seems to be at least partly controlled by FA. Nevertheless, given that FA is expressed very early during the initial vegetative phase of development, the function of this gene – promoting flower initiation in tomato – may depend on other factors only expressed during flower transition and conferring competence to the meristem.
FA controls not only flowering time and the number of nodes below the first inflorescence, but also the number of nodes between successive inflorescences. In the fa mutant the number of leaves between inflorescences is higher than in the wild type, although this decreases in later sympodial segments ( Fig. 2). The transition from vegetative to reproductive phase in tomato sympodial shoots is known to be regulated by SELF PRUNING (SP), the tomato orthologue to CENTRORADIALIS (CEN) and TERMINAL FLOWER 1 (TFL1) (Pnueli et al. 1998 ). In fact, sp mutant plants show a determinate development in which the number of leaves in the sympodial shoots is progressively reduced until two consecutive inflorescences are produced ( Pnueli et al. 1998 ). The increased number of vegetative nodes observed in fa sympodial shoots may be interpreted as the consequence of an upregulation of SP in the sympodial bud. In Arabidopsis,LFY is known to exclude TFL1 expression in the floral meristem ( Ratcliffe et al. 1999 ). In tomato, however, this exclusion does not appear to operate because the spatial and temporal expression pattern of SP ( Pnueli et al. 1998 ) is very similar to that of FA. It seems likely that vegetative or floral development in the sympodial shoot of tomato may depend on a balance between FA and SP signals in the sympodial meristem. In Arabidopsis 35S::LFY; 35S::TFL1 transgenic plants, it has recently been observed that the effect of the constitutive expression of LFY, promoting a premature acquisition of floral meristem identity, is prevented by the constitutive expression of TFL1 (Ratcliffe et al. 1999 ). In tomato, it is possible that the expression of SP in the same domains as FA prevents apical and axillary young meristems from acquiring the floral identity promoted by FA.
ฟะ fainflorescence เกิดขึ้นประมาณ 2 LFY (Blazquez et al. 1997) แต่ไม่ได้อยู่ในโฟล (Coen et al. 1990), Uni (อ็ et al. 1997) หรือ alf (Souer et al. 1998) การกลายพันธุ์ใน Arabidopsis ออกดอกเวลาของการกลาย พันธุ์ LFY, 35S :: LFY LFY เผยให้เห็นว่า LFY ควบคุมการเริ่มต้นออกดอก (Blazquez, et al. 1997; ค๊และคณะ, LFY LFY LFY กับอายุของพืช (Blazquez และคณะ LFY LFY เจริญ - -. อาจขึ้นอยู่กับปัจจัยอื่น ๆ
แต่ ฟะ แต่ลดลงในส่วน sympodial ต่อมา (รูปที่ sympodial (SP), orthologue มะเขือเทศเพื่อ CENTRORADIALIS (CEN) และเทอร์มิดอกไม้ 1 (TFL1) (Pnueli et al. 1998) ในความเป็นจริงกลายพันธุ์พืช SP sympodial (Pnueli และคณะ sympodial fa อาจถูกตีความว่าเป็นผลมาจากการ upregulation ของ SP ในตา sympodial ใน Arabidopsis, LFY TFL1 ในเนื้อเยื่อดอกไม้ (Ratcliffe et al. 1999) ในมะเขือเทศ SP (Pnueli et al. 1998) sympodial SP ใน sympodial เนื้อเยื่อใน 35S Arabidopsis :: LFY; 35S :: TFL1 ๆ LFY TFL1 (Ratcliffe และคณะ SP
การแปล กรุณารอสักครู่..