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Bannerot et al. (191'7) into this cytoplasm using intergeneric crossing followed by backcrossing. Shiga and Baba (19'71, 1973) and ThomPson (19'72) Heyn (1979) and Rouselle (1979) found that all rape cultivars tested in their studies were maintainers for the ogu CMS. Bonnet (1975) China and Japan were winter types. The seedlings from these strains were vernalized at 4 C"

FAN, Z., W. TAI, and B. R. STEFANSSON. 1985. Male sterility in Bras.sic.a napus L. associated with an extra chromosome.Can. J. Genet. Cytol. 27: 467-471.Male sterility was investigated in backcross populations from hybrids between Diplotaxis muralis and Brassica napus using the former as the female parent. The F, was male sterile and low frequencies (less than 20%) of male sterile plants were obtained from subsequent backcross generations. The data did not fit any Mendelian genetic ratios. Cytological examination of pollen mother cells from 52 plants of these backcross populations indicated the presence of an extra chromosome in all 22 male sterile plants and the normal chromosome number ( 2 n = 38) in the remaining 30 fertile plants. Thus an extra chromosome which is derived from Diplotaxis muralis appears to be the sole cause of male sterility in these backcross populations.La stkrilitk mile a kt6 ktudike chez des populations rktrocroiskes issues d'hybrides entre Diplotaxis muralis et Brassica napus en utilisant le D. muralis comme parent femelle. La F, a kt6 mile-sterile et de faibles frkquences (moins de 20%) de plantes mile-stCriles ont kt6 obtenues des gknkrations rktrocroiskes subskquentes. Ces donnkes ne concordent avec aucun des ratios gknktiques mendklkens. L'examen cytologique des cellules-mkres de pollen de 52 plantes des populations rktrocroiskes rkvkle la prksence d'un chromosome surnumkraire chez 22 plantes mile-stkriles, alors que les 30 autres plantes fertiles avaient un nombre chromosomique normal ( 2 n = 38). I1 s'ensuit que le chromosome surnumkraire qui derive de D. muralis semble etre la seule cause de la stkrilitk mile chez ces populations rktrocroiskes. Mots cle's: stkrilitk mile, Brassica napus, Diplotaxis muralis. [Traduit par le journal]

Over the past decade, the polima cytoplasmic male sterility (pol CMS) three-line and two-line systems have been developed for the production of hybrid seed in Brassica napus oilseed rape in China. The discovery of the novel pol CMS restorer line FL-204 is described here. It restores male fertility of hybrid plants in the pol CMS system, but hybrid seed production can only be carried out under autumn sowing in Wuhan in south China under moderate temperatures at flowering. The restorer cannot be used as a male for hybrid seed production in northwestern China (Gansu) under spring sowing conditions, because there it is more or less male sterile due to high temperatures at flowering. Because of this behaviour, it is referred to as a fertility temperature-sensitive restorer (FTSR) in this paper. F 2 , BC 1 as well as double haploid populations were constructed to determine the inheritance of fertility restoration of FL-204 in the autumn at Wuhan and under spring sowing conditions at Gansu, respectively. Deviations from Mendelian genetics were observed. It was hypothesized that the change of fertility was the result of the interaction between nuclear genes [restoring gene (Rf) and temperature-sensitive genes (ts)] and the cytoplasm. The Rf gene in FL-204 was incapable of restoring male fertility of pol CMS lines under spring sowing conditions at Gansu where it is inactivated by the recessive ts gene present in FL-204. However, the ts gene(s) could be non-functional under moderate temperature conditions at flowering at Wuhan which allows full expression of male fertility in FL-204. The recessive ts gene(s) can only be expressed in plants containing the pol sterile cytoplasm. A method for the utilization of the FTSR pol CMS restorer FL-204 for the production of hybrid seed in B. napus oilseed rape is proposed.

Arbuscular mycorrhizal fungi (AMF) can form a mutually beneficial symbiotic relationship with most land plants. They are known to secrete lysin motif (LysM) effectors into host root cells for successful colonization. Intriguingly, plants secrete similar types of LysM proteins; however, their role in plant–microbe interactions is unknown. Here, we show that Medicago truncatula deploys LysM extracellular (LysMe) proteins to facilitate symbiosis with AMF. Promoter analyses demonstrated that three M. truncatula LysMe genes MtLysMe1/2/3 , are expressed in arbuscule-containing cells and those adjacent to intercellular hyphae. Localization studies showed that these proteins are targeted to the periarbuscular space between the periarbuscular membrane and the fungal cell wall of the branched arbuscule. M. truncatula mutants in which MtLysMe2 was knocked out via CRISPR/Cas9-targeted mutagenesis exhibited a significant reduction in AMF colonization and arbuscule formation, whereas genetically complemented transgenic plants restored wild-type level AMF colonization. In addition, knocking out the ortholog of MtLysMe2 in tomato resulted in a similar defect in AMF colonization. In vitro binding affinity precipitation assays suggested binding of MtLysMe1/2/3 with chitin and chitosan, while microscale thermophoresis (MST) assays revealed weak binding of these proteins with chitooligosaccharides. Moreover, application of purified MtLysMe proteins to root segments could suppress chitooctaose (CO8)-induced reactive oxygen species production and expression of reporter genes of the immune response without impairing chitotetraose (CO4)-triggered symbiotic responses. Taken together, our results reveal that plants, like their fungal partners, also secrete LysM proteins to facilitate symbiosis establishment.

FAN, Z., and W. TAI. 1985. A cytogenetic study of monosomics in Brci.s.sic~ci ncipus L. Can. J. Genet. Cytol. 27: 683-688.Two types of monosomic plants of Brassica napus L. were discovered among the backcross progenies of crosses between Diplotaxis muralis L. and B. napus and between Bra.ssica juncea L. and B. napus. These monosomics were designated mono-] and mono-2, respectively. Morphologically the monosomic plants were virtually indistinguishable from their sib disomic plants. Seed production on both mono-1 and mono-2 plants was normal. Cytological examination revealed that most pollen mother cells (85%) of mono-l plants formed 18 bivalents plus one univalent at diakinesis, while the remainder (15%) formed 17 bivalents plus a trivalent. The univaltn in mono-l was submetacentric and its two arms were always stained more lightly than the centromeric region. Later meiotic stages in mono-I plants appeared normal. The plants of monol produced two types of pollen grains which were different in size. Both the large and small pollen grains of mono-I were deeply stained with an 12-K1 solution. Meiotic behavior of mono-2 plants was similar to that of mono-1 plants, but the frequency of trivalent formation was higher (62%). The univalent in mono-2 was longer than the two chromosomes it paired with to form a trivalent. Pollen produced on mono-2 plants was uniform in size and comparable to that of the normal disomics. FAN, Z., et W. TAI. 1985. A cytogenetic study of monosomics in Bras.sic.a napus L. Can. J . Genet. Cytol. 27: 683-688. Deux types de plantes monosomiques de Brassica napus L. ont etk decouverts parmi les descendants rktrocroisks issus de croisements entre Diplotaxis muralis L. et B. napus, ainsi qu'entre B. junc-eel L. et B. ncipus.Ces monosomiques furent dksignks mono-l et mono-2, respectivement. Sur le plan morphologique, les plantes monosomiques n'ont pu &re distingukes en pratique des plantes disomiques apparentees. La production de graines des plantes mono-I et mono-2 fut normale. L'examen cytologique a rkvklk que la plupart des cellules meres de pollen (85%) des plantes monol formaient 18 bivalents plus un univalent a la diacinkse, alors que les autres cellules meres (15%) formaient 17 bivalents plus un trivalent. L'univalent de plantes mono-1 ktait submktacentrique et ses deux bras ktaient toujours colorks plus Ikgerement que la rkgion centromkrique. Chez les plantes mono-I, les stades meotiques ultkrieurs ont paru normaux. D'autre part, ces plantes ont produit deux types de grains de pollen de dimensions diffkrentes; toutefois, ces grains, gros ou petits, ont etk colores intenskment par I'iodure de potassium iodk 12-KI. Le comportement mkiotique des plantes mono-2 fut semblable h celui des plantes mono-I, bien que la frkquence de formation de trivalents fut plus klevke (62%). Chez les plantes mono-2, I'univalent ktait plus long que les deux chromosomes avec lesquels il s'appariait lors de la formation des trivalents. Le pollen produit par les plantes mono-2 fut de dimension uniforme et comparable a c...

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