Aaron Rottenberg

The wild ancestry of the cultivated artichoke.

SummaryThe genetic affinities between the cultivated artichoke Cynara cardunculus L. var. scolymus (L.) Flori (= C. scolymus L.) and its wild relatives were tested by means of a crossing programme. The following wild taxa were involved: (i) wild cardoon C. carcundulus L. var. sylvestris (Lamk) Fiori, (ii) C. syriaca Boiss., (iii) C. cornigera Lindley, (iv) C. algarbiensis Cosson, (v) C. baetica (Spreng.) Pau (= C. alba Boiss.), and (vi) C. humilis L. Only the wild cardoon was found to be fully cross-compatible and fully infertile with the crop. In contrast, all other five wild Cynara species turned to be almost fully-or fully-cross-incompatible with the crop, and the few interspecific F1 hybrids recovered were partly or almost fully sterile. These finds establish the wild cardoon as the wild ancestor of the cultivated vegetable.

Isozyme relationships between cultivated artichoke and the wild relatives

SummaryThe genetic affinities between the cultivated artichoke Cynara cardunculus L. var. scolym (L.) Fiori [= C. scolymus L.] and its wild relatives were assessed by tests of 20 enzyme systems (28 loci). Six representative cultivars and the following wild taxa were examined: (i) wild cardoon C.cardunculus L. var. sylvestris (Lamk) Fiori, (ii) C. syriaca Boiss., (iii) C. cornigera (Lindley) [=C. sibthorpiana Boiss.], (iv) C. algarbiensis Cosson, (v) C. baetica (Spreng.) Pau [=C. alba Boiss.], and (vi) C. humilis L. Twenty one out of the 28 loci tested were polymorphic (mainly between species). The genetic identity between the cultivars and the wild cardoon forms ranged from 0.92 to 0.96; while that between these two taxa and the five other wild Cynara species ranged between 0.67 and 0.79. This implicates wild C. cardunculus in the wild ancestry of the cultivated artichoke.

Fertility of exceptional bisexual individuals in four dioecious plant species

Abstract Exceptional, very rare, bisexual (hermaphroditic or monoecious) individuals have been detected in strictly dioecious populations of Rhamnus alaternus, R. palaestinus, Bryonia syriaca and Populus euphratica (a single individual in each species). While ordinary male plants in each species exhibited fully normal pollen, and female individuals set a considerable amount of fruit, the exceptional bisexual plants showed a reduction in male or female fertility, or both. This inability of the rare bisexual individuals to fully invest in the two genders suggests that trade-offs between male and female functions possibly play a major role in the breeding systems of these dioecious species, and probably implicates resource allocation (among other factors) as a selective force in the evolution of dioecy.

The wild gene pool of globe artichoke

Globe artichoke is an important vegetable of the Mediterranean basin. Its primary gene pool (GP1) consists of wild types of Cynara cardunculus. Crosses between the wild types and the cultivars (artichoke and cardoon) are fully fertile. In accordance, analyses of molecular markers revealed high genetic identity between the wild types and the cultivars. Hence, all these taxa are grouped together as conspecific varieties within C. cardunculus. Several other wild Cynara species thrive in the Mediterranean basin. Of these, C. syriaca, C. algarbiensis, C. baetica and C. humilis were tested and found to be part of the secondary gene pool (GP2) of artichoke, as they were rather difficult to cross with either wild or cultivated C. cardunculus and the few hybrids obtained were semi-sterile. In accordance, molecular genetic markers suggest that these wild Cynara species indeed diverged from C. cardunculus. Four additional Cynara species thrive in the Mediterranean basin, namely C. cornigera, C. cyrenaica, C. tournef...

Patterns of Isozyme Diversity and Vegetative Reproduction of Willows in Israel

Isozyme tests were used to examine the genetic structure of six populations ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Has agriculture dispersed worldwide from a single origin

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Genetic variability in sexually dimorphic and monomorphic populations of Populus euphratica (Salicaceae)

\end{document} individuals) of the two willow species in Israel, Salix alba and Salix acmophylla. The 14 enzymes revealed 23 putative loci, of which 15 were polymorphic. Sexually dimorphic populations (females and males) and monomorphic ones (all female) were tested in these two species, with the following results: (1) The two sexually dimorphic S. alba populations were the most variable in isozymes. (2) The all‐female population of this species had lower genetic diversity. The three tested S. alba populations are part of S. albas continuous geographical distribution in the Upper Jordan Valley in Israel. Apparently, genetic variability is maintained in this area and, to some degree, also in the all‐female stand. (3) However, the sexually dimorphic S. acmophylla population showed lower isozyme diversity than the S. alba populations, probably because S. acmophylla populations in Israel tend to be smaller and more isolated than those of S. alba. (4) The two all‐female populations of S. acmophylla showed no variability at all; i.e., all 23 loci were monomorphic, indicating that each of these two populations are a single clone. The biased sex ratios, together with the relatively low values of genetic diversity and heterozygosity indicate a possible genetic drift, strong sib‐mating, and vegetative propagation in these willow populations.

A field survey of dioecious plants in Israel: sex ratio in seven rare species

Rumex rothschildianus is a small dioecious annual, a sole member of a unique section in the genus Rumex. This very rare species is restricted to the light soils of the Sharon coastal plain in Israel. Here, this endemic sorrel was recorded from only 12sites. Until thirty years ago, it still existed in nine of these 12 localities. Several visits to each of these sites between 1995 and 1999 revealed that it is surviving today only in three of them. Only in one of these three sites a considerable population of several hundred individuals was found. The other two populations contain a few dozen plants each. Hence, there is a great danger that under the heavy urbanization of the coastal plain in Israel this sorrel will soon be extinct. If so, it will be the first endemic-to-Israel plant species which will be lost, and thus will be globally extinct. Immediate conservation measures should be taken to protect this very rare sorrel.